Thank You ... Am normally wrong and am then corrected. One question ... if the substations remained above ground with a breaker to trip at the first sign of a surge would that help the situation?
If we had as little as 30 minutes warning, the operators might be able to cut their interrupters, but many super-high-voltage transformers at power stations cannot be disconnected... so they'd pop. There is one last American manufacturer of transformers, but alas, there are no spares in place at most power plants, so it's lights out for 18 months or so until the transformers could be replaced.
It's a grim scenario.
It would be better, honestly, for the Feds to laser or kinetic-kill any missile gaining altitude over the continent, and risk spewing radioactive junk all over the landscape, than to allow any nuclear weapon to be exploded at high altitude in our airspace. You can't treat radiation sickness if you have no hospitals with power, and all the doctors are gone because they are protecting their families from looters in the vast, long dark.